Confirmation of co-denitrification in grazed grassland

peer-reviewedPasture-based livestock systems are often associated with losses of reactive forms of nitrogen (N) to the environment. Research has focused on losses to air and water due to the health, economic and environmental impacts of reactive N. Di-nitrogen (N2) emissions are still poorly characterized, both in terms of the processes involved and their magnitude, due to financial and methodological constraints. Relatively few studies have focused on quantifying N2 losses in vivo and fewer still have examined the relative contribution of the different N2 emission processes, particularly in grazed pastures. We used a combination of a high 15N isotopic enrichment of applied N with a high precision of determination of 15N isotopic enrichment by isotope-ratio mass spectrometry to measure N2 emissions in the field. We report that 55.8 g N m−2 (95%, CI 38 to 77 g m−2) was emitted as N2 by the process of co-denitrification in pastoral soils over 123 days following urine deposition (100 g N m−2), compared to only 1.1 g N m−2 (0.4 to 2.8 g m−2) from denitrification. This study provides strong evidence for co-denitrification as a major N2 production pathway, which has significant implications for understanding the N budgets of pastoral ecosystems.The authors are grateful for the funding that was provided through the Research Stimulus Fund Program administered by the Department of Agriculture & Food under the National Development Plan 2007–2013 RSF 07536. The first author is grateful for the funding provided by Teagasc through the Walsh Fellowship Scheme

Refractory hyperparathyroidism with a T3 bony lesion—differential diagnoses

We report a case of severe hyperparathyroidism complicated by osteitis fibrosa cystica in an 83-year-old man post-myocardial infarction. The lesions were evident on magnetic resonance imaging only. A diagnosis of parathyroid carcinoma was considered due to clinical appearance of the parathyroid intraoperatively and the presence of an invasive T3 lesion mimicking metastatic disease. Differentiating parathyroid carcinoma from the benign causes at presentation can be difficult due to overlapping clinical, biochemical, radiological and histological features. The presence of bony lesions increases the diagnostic complexity of the case and demonstrates the challenges involved in the management of this disorder

Inclusivity in Pre-Assessment Support

An attainment gap persists between our UK domiciled white students and students of Black, Asian and Minority Ethnic groups (BAME), despite the best efforts of the inclusive curriculum framework. It has previously been identified that use of academic language can be a contributing factor to lower attainment for BAME students (Open University Annual Report, 2013) and that they may be less likely to access support (Stuart et al., 2011). I set up a SADRAS project in collaboration with students and staff to investigate the use of pre-assessment support in Sport Science courses at Kingston University and explored students’ preferences, to determine whether differences were evident between BAME and white students. Results suggested differences in both use of academic support and preferences between student groups, with availability and location highlighted as constraints of use for BAME students. The results of this preliminary study were presented at the Advance HE Assessment and Feedback Symposium, leading to further dissemination at an invited seminar with the Open University STEM Pedagogy Group (eSTEeM). I am now extending the research with a second SADRAS project, extending the analysis to undergraduate students throughout the SEC Faculty

Structural Alterations in a Component of Cytochrome c Oxidase and Molecular Evolution of Pathogenic Neisseria in Humans

Three closely related bacterial species within the genus Neisseria are of importance to human disease and health. Neisseria meningitidis is a major cause of meningitis, while Neisseria gonorrhoeae is the agent of the sexually transmitted disease gonorrhea and Neisseria lactamica is a common, harmless commensal of children. Comparative genomics have yet to yield clear insights into which factors dictate the unique host-parasite relationships exhibited by each since, as a group, they display remarkable conservation at the levels of nucleotide sequence, gene content and synteny. Here, we discovered two rare alterations in the gene encoding the CcoP protein component of cytochrome cbb3 oxidase that are phylogenetically informative. One is a single nucleotide polymorphism resulting in CcoP truncation that acts as a molecular signature for the species N. meningitidis. We go on to show that the ancestral ccoP gene arose by a unique gene duplication and fusion event and is specifically and completely distributed within species of the genus Neisseria. Surprisingly, we found that strains engineered to express either of the two CcoP forms conditionally differed in their capacity to support nitrite-dependent, microaerobic growth mediated by NirK, a nitrite reductase. Thus, we propose that changes in CcoP domain architecture and ensuing alterations in function are key traits in successive, adaptive radiations within these metapopulations. These findings provide a dramatic example of how rare changes in core metabolic proteins can be connected to significant macroevolutionary shifts. They also show how evolutionary change at the molecular level can be linked to metabolic innovation and its reversal as well as demonstrating how genotype can be used to infer alterations of the fitness landscape within a single host

Rapid epidemic expansion of the SARS-CoV-2 Omicron variant in southern Africa

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic in southern Africa has been characterised by three distinct waves. The first was associated with a mix of SARS-CoV-2 lineages, whilst the second and third waves were driven by the Beta and Delta variants, respectively1-3. In November 2021, genomic surveillance teams in South Africa and Botswana detected a new SARS-CoV-2 variant associated with a rapid resurgence of infections in Gauteng Province, South Africa. Within three days of the first genome being uploaded, it was designated a variant of concern (Omicron) by the World Health Organization and, within three weeks, had been identified in 87 countries. The Omicron variant is exceptional for carrying over 30 mutations in the spike glycoprotein, predicted to influence antibody neutralization and spike function4. Here, we describe the genomic profile and early transmission dynamics of Omicron, highlighting the rapid spread in regions with high levels of population immunity

The effect of urinary nitrogen loading rate and a nitrification inhibitor on nitrous oxide emissions from a temperate grassland soil

Nitrous oxide (N₂O) emissions associated with urine nitrogen (N) deposition during grazing are a major component of greenhouse gas emissions from domestic livestock. The present study investigated the relationship between urine N loading rate and the efficacy of a nitrification inhibitor, dicyandiamide (DCD), on cumulative N₂O emissions from a grassland soil in Ireland over 80 and 360-day periods in 2009/10 and 2010/11. A diminishing curvilinear relationship between urine N rate and cumulative N₂O emissions was observed in both years. Despite this increase in cumulative N₂O emissions, the emission factor (EF₃) for N₂O decreased with increasing urine N rate from, on average, 0·24 to 0·10% (urine applied at 300 and 1000 kg N/ha, respectively), during an 80-day measurement period. This was probably the result of a factor other than N, such as carbon (C), limiting the production of N₂O. The efficacy of DCD varied with urine N loading rate, and inter-annual variability in efficacy was also observed. Dicyandiamide was effective at reducing N₂O production for 50-80 days after urine application, which accounted for the major period of elevated daily flux. However, DCD was ineffective at reducing N₂O production after this period, which was likely a result of its removal from the soil via degradation and leaching. Copyright © Cambridge University Press 2014

Therapy using conversation analysis: helping couples adapt to Aphasia in conversation

This study focuses on the assessment and treatment of the conversations of a couple where one partner has aphasia. The assessment and treatment, informed by conversation analysis, are described, and some implications for the relation between language and psychosocial issues discussed

The fate of urine nitrogen: A grassland lysimeter study in Ireland

In grazed pasture systems, the nitrogen (N) contained in a cattle urine patch may be up to 1200 kg N ha⁻¹. The majority of this N is in excess of plant requirements and is vulnerable to environmental loss. In this study, cattle urine was applied at five rates of nitrogen, 0, 300,500, 700 and 1000 kg N ⁻¹ soil monolith lysimeters in late autumn in Ireland. Measurements of gaseous N emissions, nitrate (NO₃⁻) leaching and pasture N uptake were made for a calendar year following urine application in two consecutive experiments. Increasing the rate of urine N applied increased the cumulative nitrous oxide (N₂O) emissions, NO₃⁻ leaching and pasture N uptake in years one and two, and the relationships were curvilinear with N recovery diminishing at the higher N rates

The fate of urine nitrogen with use of a nitrification inhibitor

Pasture-grazed ruminants in Ireland contribute a significant proportion of nitrogen (N) loss to the environment through excreta deposition. Feed N utilisation by the ruminant animal is low with 60-90% of ingested N returned to the soil/pasture system in the excreta, particularly in the urine (Haynes and Williams, 1993). The urine N loading rate in a single cattle urine patch is approximately 1000 kg N ha⁻¹ (Haynes and Williams, 1993). N balance studies have estimated the fate of urine N on a range of soils (Clough et al., 1998). Application of dicyandiamide (DCD) nitrification inhibitor has consistently reduced N leaching and N2O emissions from urine patches (Di and Cameron,2007; de Klein et al., 2011), but produced variable pasture N responses (Di and Cameron, 2007; Zaman and Blennerhassett, 2010). A ¹⁵N balance study was conducted on grassland lysimeters in Ireland to investigate the fate of urine N with and without the application of DCD nitrification inhibitor